U.S. patent application number 13/840355 was filed with the patent office on 2014-07-17 for feed network.
This patent application is currently assigned to Tyco Electronics Corporation. The applicant listed for this patent is Bruce Foster Bishop, Kathleen Fasenfest. Invention is credited to Bruce Foster Bishop, Kathleen Fasenfest.
Application Number | 20140197901 13/840355 |
Document ID | / |
Family ID | 51164705 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140197901 |
Kind Code |
A1 |
Bishop; Bruce Foster ; et
al. |
July 17, 2014 |
Feed Network
Abstract
A feed network includes three radio frequency (RF) devices
constructed in a suspended-substrate stripline configuration that
provides a five-port microwave device having a sum port and four
feed ports. The three RF devices include at least one coupled-line
quadrature hybrid and at least one Marchand balun. Each of the at
least one coupled-line quadrature hybrid has only a single
transmission line section providing two outputs with approximately
equal amplitude power and a phase difference of 90.degree.. Each of
the at least one Marchand balun includes two offset-coupled
transmission line sections separated by a gap and two outputs on
opposite sides of the gap. The two outputs have approximately equal
amplitude power and a phase difference of 180.degree.. The three RF
devices are electrically arranged relative to the sum port and the
four feed ports such that the feed ports have equal amplitude power
and a progressive 90.degree. phase shift.
Inventors: |
Bishop; Bruce Foster;
(Aptos, CA) ; Fasenfest; Kathleen; (Union City,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bishop; Bruce Foster
Fasenfest; Kathleen |
Aptos
Union City |
CA
CA |
US
US |
|
|
Assignee: |
Tyco Electronics
Corporation
Berwyn
PA
|
Family ID: |
51164705 |
Appl. No.: |
13/840355 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61752931 |
Jan 15, 2013 |
|
|
|
Current U.S.
Class: |
333/117 |
Current CPC
Class: |
H01P 5/12 20130101; H01P
5/10 20130101 |
Class at
Publication: |
333/117 |
International
Class: |
H01P 5/22 20060101
H01P005/22 |
Claims
1. A feed network comprising: three radio frequency (RF) devices
constructed in a suspended-substrate stripline configuration that
provides a five-port microwave device having a sum port and four
feed ports, the three RF devices including at least one
coupled-line quadrature hybrid and at least one Marchand balun;
wherein each of the at least one coupled-line quadrature hybrid has
only a single transmission line section providing two outputs with
approximately equal amplitude power and a phase difference of
90.degree.; wherein each of the at least one Marchand balun
includes two offset-coupled transmission line sections separated by
a gap and two outputs on opposite sides of the gap, the two outputs
having approximately equal amplitude power and a phase difference
of 180'; and wherein the three RF devices are electrically arranged
relative to the sum port and the four feed ports such that the feed
ports have equal amplitude power and a progressive 90.degree. phase
shift.
2. The feed network of claim 1, wherein the at least one
coupled-line quadrature hybrid is a single coupled-line quadrature
hybrid and the at least one Marchand balun is two Marchand
baluns.
3. The feed network of claim 1, wherein the at least one Marchand
balun is a single Marchand balun and the at least one coupled-line
quadrature hybrid is two coupled-line quadrature hybrids.
4. The feed network of claim 1, wherein the four feed ports
comprise first, second, third, and fourth feed ports, the at least
one Marchand balun is a single Marchand balun, and the at least one
coupled-line quadrature hybrid comprises first and second
coupled-line quadrature hybrids, the Marchand balun being
electrically connected between the sum port and the first and
second coupled-line quadrature hybrids and being configured to
divide an input RF signal into first and second intermediate RF
signals with approximately equal power amplitudes and a phase
difference of 180.degree., the first coupled-line quadrature hybrid
being electrically connected between the Marchand balun and the
first and second feed ports and being configured to divide the
first intermediate RF signal into first and second feed RF signals
having phases of 0.degree. and 90.degree., respectively, the second
coupled-line quadrature hybrid being electrically connected between
the Marchand balun and the third and fourth feed ports and being
configured to divide the second intermediate RF signal into third
and fourth feed RF signals having phases of 180.degree. and
270.degree., respectively.
5. The feed network of claim 1, wherein the four feed ports
comprise first, second, third, and fourth feed ports, the at least
one coupled-line quadrature hybrid is a single coupled-line
quadrature hybrid, and the at least one Marchand balun comprises
first and second Marchand baluns, the coupled-line quadrature
hybrid being electrically connected between the input port and the
first and second Marchand baluns and being configured to divide an
input RF signal into first and second intermediate RF signals with
approximately equal power amplitudes and a phase difference of
90.degree., the first Marchand balun being electrically connected
between the coupled-line quadrature hybrid and the first and third
feed ports and being configured to divide the first intermediate RF
signal into first and third feed RF signals having phases of
0.degree. and 180.degree., respectively, the second Marchand balun
being electrically connected between the coupled-line quadrature
hybrid and the second and fourth feed ports and being configured to
divide the second intermediate RF signal into second and fourth
feed RF signals having phases of 90.degree. and 270.degree.,
respectively.
6. The feed network of claim 1, wherein the transmission line
section of the at least one coupled-line quadrature hybrid is a
uniformly-coupled transmission line section.
7. The feed network of claim 1, wherein the transmission line
section of the at least one coupled-line quadrature hybrid is a
non-uniformly coupled transmission line section.
8. The feed network of claim 1, wherein each of the transmission
line sections of the at least one Marchand balun is a
uniformly-coupled transmission line section.
9. The feed network of claim 1, wherein each of the transmission
line sections of the at least one Marchand balun is a non-uniformly
coupled transmission line section.
10. The feed network of claim 1, wherein the transmission line
section of the at least one coupled-line quadrature hybrid includes
two transmission line segments that are offset coupled.
11. The feed network of claim 1, wherein the transmission line
section of the at least one coupled-line quadrature hybrid includes
two transmission line segments that are broadside coupled.
12. The feed network of claim 1, wherein the at least one
coupled-line quadrature hybrid has a characteristic impedance that
is different than a characteristic impedance of at least one of the
sum port or the feed ports.
13. The feed network of claim 1, wherein the transmission line
section of the at least one coupled-line quadrature hybrid has an
electrical length of one-quarter of a wavelength at the center
frequency of operation.
14. The feed network of claim 1, wherein each transmission line
section of the at least one Marchand balun has an electrical length
of one-quarter of a wavelength at the center frequency of
operation.
15. The feed network of claim 1, wherein the feed network is
configured to operate over a bandwidth of at least approximately
10%.
16. The feed network of claim 1, wherein the feed network has a
width of less than approximately 51 mm (2.0 inches).
17. A feed network comprising: three radio frequency (RF) devices
constructed in a suspended-substrate stripline configuration that
provides a five-port microwave device having a sum port and four
feed ports, the three RF devices comprising: first and second
coupled-line quadrature hybrids each having only a single
transmission line section that provides two outputs with
approximately equal amplitude power and a phase difference of
90.degree.; and a Marchand balun having two offset-coupled
transmission line sections separated by a gap and two outputs on
opposite sides of the gap, the two outputs having approximately
equal amplitude power and a phase difference of 180.degree.,
wherein the Marchand balun and the first and second coupled-line
quadrature hybrids are electrically arranged relative to the sum
port and the four feed ports such that the feed ports have equal
amplitude power and a progressive 90.degree. phase shift.
18. The feed network of claim 17, wherein the four feed ports
comprise first, second, third, and fourth feed ports, the Marchand
balun being electrically connected between the sum port and the
first and second coupled-line quadrature hybrids, the Marchand
balun being configured to divide an input RF signal into first and
second intermediate RF signals with approximately equal power
amplitudes and a phase difference of 180.degree., the first
coupled-line quadrature hybrid being electrically connected between
the Marchand balun and the first and second feed ports, the first
coupled-line quadrature hybrid being configured to divide the first
intermediate RF signal into first and second feed RF signals having
phases of 0.degree. and 90.degree., respectively, the second
coupled-line quadrature hybrid being electrically connected between
the Marchand balun and the third and fourth feed ports, the second
coupled-line quadrature hybrid being configured to divide the
second intermediate RF signal into third and fourth feed RF signals
having phases of 180.degree. and 270.degree., respectively.
19. A feed network comprising: three radio frequency (RF) devices
constructed in a suspended-substrate stripline configuration that
provides a five-port microwave device having a sum port and four
feed ports, the three RF devices comprising: first and second
Marchand baluns each having two offset-coupled transmission line
sections separated by a gap and two outputs on opposite sides of
the gap, the two outputs having approximately equal amplitude power
and a phase difference of 180.degree., and a coupled-line
quadrature hybrids having only a single transmission line section
that provides two outputs with approximately equal amplitude power
and a phase difference of 90.degree., wherein the coupled-line
quadrature hybrid and the first and second marchand baluns are
electrically arranged relative to the sum port and the four feed
ports such that the feed ports have equal amplitude power and a
progressive 90.degree. phase shift.
20. The feed network of claim 19, wherein the four feed ports
comprise first, second, third, and fourth feed ports, the
coupled-line quadrature hybrid being electrically connected between
the sum port and the first and second Marchand baluns, the
coupled-line quadrature hybrid being configured to divide an input
RF signal into first and second intermediate RF signals with
approximately equal power amplitudes and a phase difference of
90.degree., the first Marchand balun being electrically connected
between the coupled-line quadrature hybrid and the first and third
feed ports, the first Marchand balun being configured to divide the
first intermediate RF signal into first and third feed RF signals
having phases of 0.degree. and 180.degree., respectively, the
second Marchand balun being electrically connected between the
coupled-line quadrature hybrid and the second and fourth feed
ports, the second Marchand balun being configured to divide the
second intermediate RF signal into second and fourth feed RF
signals having phases of 90.degree. and 270.degree., respectively.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from provisional
Application No. 61/752,931, filed Jan. 15, 2013, the disclosure of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The subject matter disclosed herein relates generally to
transmission line circuitry, and more particularly to feed networks
for antennas.
[0003] Various types of feed networks are used to feed radio
frequency (RF) energy between one or more antennas and associated
processing systems, such as transmitters, receivers, and/or
transceivers. For example, a feed network may convert RF waves
received by an antenna into RF electrical signals and deliver the
RF electrical signals to the processing system, and/or vice versa.
Known feed networks may include one or more various components for
controlling the amplitude and phase of RF power at the antenna(s),
and may include RF devices such as baluns, hybrid couplers, delay
lines, phase shifters, and/or the like.
[0004] Known feed networks are not without disadvantages. For
example, a plurality of antennas are often grouped together in an
array. Each antenna typically includes a dedicated feed network
that serves that particular antenna. Accordingly, the antenna array
typically includes a plurality of antenna and feed network pairs.
But, there may be a limited amount of space for containing the
antenna and feed network pairs, which may limit the minimum spacing
between antennas in an array. For example, the length, width,
and/or a similar dimension (e.g., a diameter and/or the like) of at
least some known feed networks may limit the minimum spacing
between antennas in an array. Electronically-steerable antenna
arrays exhibit grating lobes in at least some angular regions for
antenna element spacings greater than one-half of a wavelength at
the frequency of operation. Thus, the minimum spacing between
antenna elements can determine the maximum operating frequency of
an antenna array.
[0005] Another disadvantage of at least some known feed networks is
bandwidth. Specifically, the operational frequency band of at least
some known feed networks may be too narrow to enable the associated
antenna to communicate with one or more devices.
[0006] Another disadvantage of at least some known feed networks is
fabrication cost. Specifically, at least some known feed networks
require manual assembly, lumped-element RF devices, and/or a high
layer count (e.g., greater than four) printed circuit(s) with
single or multiple lamination cycles.
BRIEF DESCRIPTION OF THE INVENTION
[0007] In one embodiment, a feed network includes three radio
frequency (RF) devices constructed in a suspended-substrate
stripline configuration that provides a five-port microwave device
having a sum port and four feed ports. The three RF devices include
at least one coupled-line quadrature hybrid and at least one
Marchand balun. Each of the at least one coupled-line quadrature
hybrid has only a single transmission line section providing two
outputs with approximately equal amplitude power and a phase
difference of 90.degree.. Each of the at least one Marchand balun
includes two offset-coupled transmission line sections separated by
a gap and two outputs on opposite sides of the gap. The two outputs
have approximately equal amplitude power and a phase difference of
180.degree.. The three RF devices are electrically arranged
relative to the sum port and the four feed ports such that the feed
ports have equal amplitude power and a progressive 90.degree. phase
shift.
[0008] In another embodiment, a feed network includes three radio
frequency (RF) devices constructed in a suspended-substrate
stripline configuration that provides a five-port microwave device
having a sum port and four feed ports. The three RF devices include
first and second coupled-line quadrature hybrids each having only a
single transmission line section that provides two outputs with
approximately equal amplitude power and a phase difference of
90.degree.. The three RF devices also include a Marchand balun
having two offset-coupled transmission line sections separated by a
gap and two outputs on opposite sides of the gap. The two outputs
have approximately equal amplitude power and a phase difference of
180.degree.. The Marchand balun and the first and second
coupled-line quadrature hybrids are electrically arranged relative
to the sum port and the four feed ports such that the feed ports
have equal amplitude power and a progressive 90.degree. phase
shift.
[0009] In another embodiment, a feed network includes three radio
frequency (RF) devices constructed in a suspended-substrate
stripline configuration that provides a five-port microwave device
having a sum port and four feed ports. The three RF devices include
first and second
[0010] Marchand baluns each having two offset-coupled transmission
line sections separated by a gap and two outputs on opposite sides
of the gap. The two outputs have approximately equal amplitude
power and a phase difference of 180.degree.. The three RF devices
also include a coupled-line quadrature hybrids having only a single
transmission line section that provides two outputs with
approximately equal amplitude power and a phase difference of
90.degree.. The coupled-line quadrature hybrid and the first and
second Marchand baluns are electrically arranged relative to the
sum port and the four feed ports such that the feed ports have
equal amplitude power and a progressive 90.degree. phase shift.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic block diagram of an exemplary
embodiment of a feed network.
[0012] FIG. 2 is a perspective view of an exemplary embodiment of a
printed circuit that defines an exemplary embodiment of a
suspended-substrate stripline configuration of the feed network
shown in FIG. 1.
[0013] FIG. 3 is a cross-sectional view of the printed circuit
shown in FIG. 2.
[0014] FIGS. 4a-e are plan views of exemplary embodiments of
various layers of the printed circuit shown in FIGS. 2 and 3.
[0015] FIG. 5 is a plan view of the printed circuit shown in FIGS.
2-4.
[0016] FIG. 6 is a schematic block diagram of another exemplary
embodiment of a feed network.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIG. 1 is a schematic block diagram of an exemplary
embodiment of a feed network 12. The feed network 12 may have a
wide variety of applications, such as, but not limited to, driving
one or more antennas, use with microwave circuits, and/or the like.
The feed network 12 includes at least three radio frequency (RF)
devices constructed in a suspended-substrate stripline
configuration. As used herein, a "suspended-substrate stripline
configuration" is intended to mean a multi-layered printed circuit
stackup having an upper substrate core that provides two conductive
layers, a lower substrate core that provides another two conductive
layers, and one or more dielectric bonding layers that provide
physical separation between the upper and lower substrate cores. An
exemplary suspended-substrate stripline configuration is shown in
FIG. 3. In the exemplary embodiment of the feed network 12, the
feed network 12 includes an input port 30, four feed ports 32, a
Marchand balun 34, and two coupled-line quadrature hybrids 36.
Accordingly, in the exemplary embodiment of the feed network 12,
the three RF devices include only a single Marchand balun 34 and
two coupled-line quadrature hybrids 36. The four exemplary feed
ports 32 are labeled as feed ports 32a, 32b, 32c, and 32d, while
the two coupled-line quadrature hybrids 36 are labeled as
coupled-line quadrature hybrids 36a and 36b. The input port 30 may
be referred to herein as a "sum port". The Marchand balun 34 may be
referred to herein as a "first" balun. The coupled-line quadrature
hybrids 36a and 36b may each be referred to herein as a "first"
and/or a "second" quadrature hybrid. Each of the feed ports 32 may
be referred to herein as a "first", a "second", a "third", and/or a
"fourth" feed port.
[0018] The Marchand balun 34 and the coupled-line quadrature
hybrids 36 are operatively connected between the input port 30 and
the feed ports 32 for feeding RF energy between the input port 30
and the feed ports 32. The Marchand balun 34 of the feed network 12
is configured to divide an RF signal into two RF signals that have
approximately equal power amplitudes and are separated by a phase
difference of 180.degree.. Each of the coupled-line quadrature
hybrids 36 is configured to divide an RF signal into two RF signals
that have approximately equal power amplitudes with a phase
difference of 90.degree.. For purposes of the present disclosure,
the term "RF" is used broadly to include a wide range of
electromagnetic transmission frequencies including, for instance,
those falling within the radio frequency, microwave or millimeter
wave frequency ranges.
[0019] The Marchand balun 34 and the coupled-line quadrature
hybrids 36 are electrically arranged relative to the input port 30
and the feed ports 32 such that the four feed ports 32 have
approximately equal amplitude power and a progressive 90.degree.
phase shift. For example, in the exemplary embodiment of the feed
network 12, the Marchand balun 34 is electrically connected between
the input port 30 and the coupled-line quadrature hybrids 36, while
the coupled-line quadrature hybrids 36 are electrically connected
between the Marchand balun 34 and the feed ports 32. Specifically,
and as shown in FIG. 1, the Marchand balun 34 is electrically
connected between the input port 30 and each of the coupled-line
quadrature hybrids 36a and 36b. The coupled-line quadrature hybrid
36a is electrically connected between the Marchand balun 34 and the
feed ports 32a and 32b. The coupled-line quadrature hybrid 36b is
electrically connected between the Marchand balun 34 and the feed
ports 32c and 32d.
[0020] During operation of the feed network 12, the Marchand balun
34 receives an input RF signal 38 from the input port 30. The
Marchand balun 34 divides the input RF signal 38 into two
intermediate RF signals 40 and 42 that have approximately equal
power amplitudes and are separated by a phase difference of
180.degree.. The intermediate RF signals 40 and 42 have respective
phases of 0.degree. and 180.degree., relative to the phase of input
RF signal 38. The feed network 12 includes circuit elements 44 and
46 where the Marchand balun 34 outputs the intermediate RF signals
40 and 42, respectively. The intermediate RF signal 40 may be
referred to herein as a "first" intermediate RF signal, while the
intermediate RF signal 42 may be referred to herein as a "second"
intermediate RF signal. As described in more detail below in
connection with FIGS. 4a-4e, "circuit elements" may be conductive
lines, traces, segments, and/or the like formed as part of various
layers of a printed circuit. The circuit elements 44 and 46 may
each be referred to herein as an "output".
[0021] The coupled-line quadrature hybrid 36a is electrically
connected to the circuit element 44 for receiving the intermediate
RF signal 40 from the Marchand balun 34. The coupled-line
quadrature hybrid 36a divides the intermediate RF signal 40 into
two feed RF signals 48 and 50 that have approximately equal
amplitudes and are separated by a phase difference of 90.degree..
Specifically, the feed RF signals 48 and 50 have phases of
0.degree. and 90.degree., respectively. The feed port 32a is
electrically connected to a circuit element 52 of the feed network
12 where the coupled-line quadrature hybrid 36a outputs the feed RF
signal 48. The feed port 32a receives the feed RF signal 48 from
the coupled-line quadrature hybrid 36a via the circuit element 52
such that the feed port 32a is configured with the 0.degree. phase
of the feed RF signal 48. The feed RF signal 48 may be referred to
herein as "first" feed RF signal. The circuit element 52 may be
referred to herein as an "output".
[0022] The feed port 32b is electrically connected to a circuit
element 54 of the feed network 12 where the coupled-line quadrature
hybrid 36a outputs the feed RF signal 50. The feed port 32b
receives the feed RF signal 50 from the coupled-line quadrature
hybrid 36a via the circuit element 54 such that the feed port 32b
is configured with the 90.degree. phase of the feed RF signal 50.
The feed RF signal 50 may be referred to herein as "second" feed RF
signal. The circuit element 54 may be referred to herein as an
"output".
[0023] The coupled-line quadrature hybrid 36b is electrically
connected to the circuit element 46 for receiving the second
intermediate RF signal 42 from the Marchand balun 34. The
coupled-line quadrature hybrid 36b divides the second intermediate
RF signal 42 into two feed RF signals 56 and 58 that have
approximately equal power amplitudes and have a phase difference of
90.degree.. Specifically, the feed RF signals 56 and 58
respectively have phases of 180.degree. and 270.degree., relative
to the phase of the input signal 38. The feed port 32c is
electrically connected to a circuit element 60 of the feed network
12 wherein the coupled-line quadrature hybrid 36b outputs the feed
RF signal 56. The feed port 32c receives the feed RF signal 56 from
the coupled-line quadrature hybrid 36b via the circuit element 60.
The feed port 32c thus is configured with the 180.degree. phase of
the feed RF signal 56. The feed port 32d is electrically connected
to a circuit element 62 of the feed network 12 for receiving the
feed RF signal 58 from the coupled-line quadrature hybrid 36b. The
feed port 32d thus is configured with the 270.degree. phase of the
feed RF signal 58. The feed RF signals 56 and 58 may be referred to
herein as "third" and "fourth" feed RF signals, respectively. The
circuit elements 60 and 62 may be referred to herein as an
"output".
[0024] As should be appreciated from the above description and FIG.
1, the Marchand balun 34 and the coupled-line quadrature hybrids
36a and 36b are electrically arranged relative to the input port 30
and the feed ports 32 such that feed network 12 is configured with
feed ports 32 of approximately equal power amplitude and a
progressive 90.degree. phase shift of 0.degree., 90.degree.,
180.degree., and 270.degree.. The angular direction of the
progressive phase shift may be either a right hand direction (e.g.,
counter-clockwise) or a left hand direction (e.g., clockwise).
Whether a right hand direction is considered clockwise or
counter-clockwise, and whether a left hand direction is considered
clockwise or counter-clockwise, will depend on the orientation of
the feed network 12.
[0025] Each coupled-line quadrature hybrid 36a and 36b may have any
characteristic impedance, such as, but not limited to,
approximately 70.7 Ohms, approximately 50 Ohms, and/or the like. In
some embodiments, the coupled-line quadrature hybrid 36a and/or 36b
has a characteristic impedance that is different than a
characteristic impedance of the input port 30 and/or the feed ports
32. For example, in the exemplary embodiment of the feed network
12, the coupled-line quadrature hybrids 36a and 36b each have a
characteristic impedance of approximately 70.7 Ohms, while the
input port 30 and the feed ports 32 each have a characteristic
impedance of approximately 50 Ohms.
[0026] In the exemplary embodiment of the feed network 12, each of
the coupled-line quadrature hybrids 36a and 36b includes only a
single transmission line section (e.g., the transmission line
sections 150 or 152 shown in FIG. 5), which is formed by two
transmission line segments (e.g., the segments 88 and 94 shown in
FIGS. 4d and 4b, respectively, or the segments 90 and 96 shown
FIGS. 4d and 4b, respectively). The single transmission line
section of the coupled-line quadrature hybrid 36a may be a
uniformly-coupled transmission line section or may be a
non-uniformly coupled transmission line section. Similarly, the
single transmission line section of the coupled-line quadrature
hybrid 36b may be a uniformly-coupled transmission line section or
may be a non-uniformly coupled transmission line section. The two
transmission line segments of the transmission line section of the
coupled-line quadrature hybrid 36a may be offset coupled (i.e.,
offset from each other in the x and/or y direction) or may be
broadside coupled (i.e., aligned with each other in the x and y
directions). Similarly, the two transmission line segments of the
transmission line section of the coupled-line quadrature hybrid 36b
may be offset coupled or may be broadside coupled. The transmission
line section of each coupled-line quadrature hybrid 36a and 36b may
have any electrical length. In the exemplary embodiment of the feed
network 12, the transmission line section of each of the
coupled-line quadrature hybrids 36a and 36b has an electrical
length of one-quarter of a wavelength at the center frequency of
operation. Examples of other electrical lengths of the transmission
line section of each coupled-line quadrature hybrid 36 include, but
are not limited to, three-quarters of a wavelength, five-quarters
of a wavelength, and/or the like. In some alternative embodiments,
the coupled-line quadrature hybrid 36a and/or the coupled-line
quadrature hybrid 36b includes more than one transmission line
section. For example, multiple transmission line sections having
electrical lengths of one-quarter of a wavelength may be connected
in series to widen the bandwidth of a coupled-line quadrature
hybrid 36. In various embodiments, the electrical length of the
transmission line section of a uniformly-coupled transmission line
section, or the total electrical length of multiple
uniformly-coupled transmission line sections, of a coupled-line
quadrature hybrid 36 should be some substantially odd integer
multiple of a quarter of a wavelength. However, in some other
embodiments, the electrical length of the transmission line section
of a uniformly-coupled transmission line section, or the total
electrical length of multiple uniformly-coupled transmission line
sections, of a coupled-line quadrature hybrid 36 is shorter than a
quarter of a wavelength. In such embodiments wherein the electrical
length is shorter than a quarter of a wavelength, the coupled-line
quadrature hybrid 36 operates in a non-ideal condition that may
provide acceptable performance in some circumstances. In various
embodiments, the electrical length of the transmission line section
of a non-uniformly-coupled transmission line section, or the total
electrical length of multiple non-uniformly-coupled transmission
line sections, of a coupled-line quadrature hybrid 36 will be
arbitrary. The transmission line section of each of the coupled
line quadrature hybrids 36a and 36b may be referred to herein as a
"quadrature coupler".
[0027] In the exemplary embodiment of the feed network 12, the
Marchand balun 34 includes two transmission line sections (e.g.,
the transmission line sections 154 or 156 shown in FIG. 5). Each
transmission line section of the Marchand balun 34 may be a
uniformly-coupled transmission line section or may be a
non-uniformly coupled transmission line section. The two
transmission line segments of each transmission line section of the
Marchand balun 34 may be offset coupled or may be broadside
coupled. Each transmission line section of the Marchand balun 34
may have any electrical length. In the exemplary embodiment of the
feed network 12, each transmission line section of the Marchand
balun 34 has an electrical length of one-quarter of a wavelength at
the center frequency of operation. Examples of other electrical
lengths of each transmission line section of the Marchand balun 34
include, but are not limited to, three-quarters of a wavelength,
five-quarters of a wavelength, and/or the like. The Marchand balun
34 may include more than two transmission line sections in some
alternative embodiments. In some embodiments, the Marchand balun 34
includes multiple transmission line sections having electrical
lengths of one-quarter of a wavelength that are connected in series
to widen the bandwidth of the Marchand balun 34. In various
embodiments, the electrical length of the transmission line section
of a uniformly-coupled transmission line section, or the total
electrical length of multiple uniformly-coupled transmission line
sections, of a Marchand balun 34 should be some substantially odd
integer multiple of a quarter of a wavelength. However, in some
other embodiments, the electrical length of the transmission line
section of a uniformly-coupled transmission line section, or the
total electrical length of multiple uniformly-coupled transmission
line sections, of a Marchand balun 34 is shorter than a quarter of
a wavelength. In such embodiments wherein the electrical length is
shorter than a quarter of a wavelength, the Marchand balun 34
operates in a non-ideal condition that may provide acceptable
performance in some circumstances. In various embodiments, the
electrical length of the transmission line section of a
non-uniformly-coupled transmission line section, or the total
electrical length of multiple non-uniformly-coupled transmission
line sections, of a Marchand balun 34 will be arbitrary.
[0028] The feed network 12 may operate over any frequency band
including, but not limited to, any frequency band between 200 MHz
and 60 GHz. By "operate", it is meant that the feed network is
capable of combining RF power from the four feed ports 32 into the
input port 30, or dividing power from the input port 30 into the
four feed ports 32. The feed network 12 may have an increased
bandwidth as compared to at least some known feed networks. For
example, some known feed networks have a bandwidth of up to only
approximately 10%. In some embodiments, the feed network 12 is
capable of operating over bandwidths greater than 70%.
[0029] The particular RF devices, including the Marchand balun 34
and the coupled-line quadrature hybrids 36, may facilitate
providing the feed network 12 with predetermined operating
frequencies and/or with a predetermined bandwidth, for example the
increased bandwidth relative to at least some known feed networks.
Various other parameters of the feed network 12 may be selected to
provide the feed network 12 with predetermined operating
frequencies and/or with a predetermined bandwidth, for example to
provide the increased bandwidth and/or reduced size relative to at
least some known feed networks. For example, the electrical length
of the coupled-line quadrature hybrid 36a and/or 36b, the
electrical length of the Marchand balun 34, and/or the like may be
selected to provide the feed network 12 with predetermined
operating frequencies. The number of transmission line sections in
the coupled-line quadrature hybrid 36a, the number of transmission
line sections in the coupled-line quadrature hybrid 36b, the number
of transmission line sections in the Marchand balun 34, and/or the
like may be selected to provide the feed network 12 with a
predetermined bandwidth.
[0030] The feed network 12 may have any size. For example, the
overall x dimension of the feed network 12 and the overall y
dimension of the feed network 12 may each have any value. Examples
of the values of each of the overall x dimension and the overall y
dimension of the feed network 12 include, but are not limited to,
less than approximately 51 mm (2.0 inches), less than approximately
38.1 mm (1.5 inches), less than approximately 25 mm (1 inch),
between approximately 25 mm (1 inch) and approximately 51 mm (2.0
inches), and/or the like. It should be understood that the
exemplary dimensions described herein of the feed network 12 are
applicable to a feed network 12 having any shape in the x and y
dimensions. The feed network 12 may be smaller than at least some
known feed networks. For example, at least some known feed networks
have x and/or y dimensions that are at least 51 mm (2.0
inches).
[0031] Various parameters of the feed network 12 may be selected to
provide the feed network 12 with a predetermined size, for example
with predetermined values for the x and y dimensions. For example,
the use of one or more Marchand baluns 34 and the use of one or
more coupled-line quadrature hybrids 36 may be selected to provide
the feed network 12 with the predetermined size, for example to
provide the reduced size as compared to at least some known feed
networks. In one specific example, the use of one or more hybrids
36 that is a quadrature hybrid designed for a characteristic
impedance of 70.7 Ohms enables the maximum coupling of the
coupled-line quadrature hybrids 36 to exceed that otherwise
possible, which accomplishes an approximately 3 dB power division
with only a single transmission line section (e.g., having an
electrical length of one-quarter of a wavelength). The use of only
a single transmission line section according to a specific
embodiment, as opposed to the two transmission line sections
arranged in tandem in at least some known feed networks, may reduce
the size of each of the coupled-line quadrature hybrids 36, and
thus the feed network 12 overall.
[0032] The Marchand balun 34, the coupled-line quadrature hybrids
36, the input port 30, the feed ports 32, and/or any other
components of the feed network 12 may have any electrical
arrangement that enable the feed ports 32 of the feed network 12 to
have approximately equal amplitude power and a progressive
90.degree. phase shift. For example, FIG. 2 is a perspective view
of an exemplary embodiment of a printed circuit 64 that defines an
exemplary embodiment of a suspended-substrate stripline
configuration of the feed network 12. The printed circuit 64
includes the input port 30, the Marchand balun 34, the coupled-line
quadrature hybrids 36a and 36b, and the feed ports 32a, 32b, 32c,
and 32d. The printed circuit 64 also includes the circuit elements
44, 46, 52, 54, 60, and 62. The feed network 12 is not limited to
the printed circuit 64 or the electrical arrangement shown in FIG.
2. Rather, the printed circuit 64 and the electrical arrangement
shown in FIG. 2 are meant as exemplary only. Other configurations,
arrangements, and/or the like may be used.
[0033] FIG. 3 is a cross-sectional view of the printed circuit 64.
The printed circuit 64 includes a circuit element layer 66, a
dielectric bonding layer 68, and a circuit element layer 70
arranged in a stack with the bonding layer 68 extending between the
circuit element layers 66 and 70. The bonding layer 68 extends a
thickness T along a central axis 72 of the printed circuit 64. The
circuit element layers 66 and 70 are spaced apart from each other
by a gap in the x-z plane that is defined by the thickness T of the
bonding layer 68. The circuit element layers 66 and 70 may each be
referred to herein as a "first" and/or a "second" layer.
[0034] Each of the circuit element layers 66 and 70 includes a
respective dielectric substrate 74 and 76 and a respective circuit
element sub-layer 78 and 80 extending on a respective side 82 and
84 of the substrate 74 and 76, respectively. As can be seen in FIG.
3, the sides 82 and 84 oppose (i.e., face) each other. The circuit
element sub-layer 78 of the circuit element layer 66 includes a
transmission line segment 86 and a transmission segment 87 that
define portions of the Marchand balun 34. The circuit element
sub-layer 78 also includes a transmission line segment 88 and a
transmission line segment 90 that define portions of the
coupled-line quadrature hybrid 36a and the coupled-line quadrature
hybrid 36b, respectively. Similarly, the circuit element sub-layer
80 of the circuit element layer 70 include a transmission line
segment 92 and a transmission line segment 93 that define portions
of the Marchand balun 34. The circuit element sub-layer 80 also
includes a transmission line segment 94 and a transmission line
segment 96 that define portions of the coupled-line quadrature
hybrid 36a and the coupled-line quadrature hybrid 36b,
respectively. The transmission line segments 86, 87, 88, and 90 and
the transmission line segments 92, 93, 94, and 96 are better
illustrated in FIGS. 4d and 4b, respectively.
[0035] The printed circuit 64 includes two or more electrically
conductive ground plane layers 98. In the exemplary embodiment, the
printed circuit 64 includes two ground plane layers 98a and 98b.
The ground plane layer 98a extends on a side 100 of the substrate
74 that is opposite the side 82. The ground plane layer 98b extends
on a side 102 of the substrate 76 that is opposite the side 84.
Although two ground plane layers are shown, the printed circuit 64
may include any number of ground plane layers 98, each of which may
be an external layer (as is shown in FIG. 3) or an internal layer
of the printed circuit 64. Moreover, although shown and described
herein as having four layers, the printed circuit 64 may include
any number of layers. For example, the printed circuit 64 may
include any number of bonding layers 68 and/or more than two
dielectric substrates 74 and 76.
[0036] FIGS. 4a-e are plan views of the various layers of the
printed circuit 64. Specifically, FIGS. 4a and 4e illustrate the
ground plane layers 98a and 98b, respectively. The ground plane
layers 98a and 98b may each include one or more openings, vias,
and/or other structures 104 and 106, respectively, that enable
electrical and/or other connections to be made to the printed
circuit 64, for example at the input port 30, the feed ports 32,
and/or the like. The ground plane layers 98a and 98b and the
circuit element layers 70 and 66 are each electrically conductive
and may each be fabricated from any electrically conductive
material containing or comprising metals, such as, but not limited
to, copper, gold, silver, aluminum, tin, and/or the like.
[0037] FIG. 4b illustrates the circuit element layer 70. The side
84 of the substrate 76 having the circuit element layer 70 is
visible in FIG. 4b. The circuit element sub-layer 80 extends on the
side 84 and includes the transmission line segment 92, the
transmission line segment 93, the transmission line segment 94, and
the transmission line segment 96. As described above, the segments
92 and 93 define portions of the Marchand balun 34 and the segments
94 and 96 define portions of the coupled-line quadrature hybrid 36a
and the coupled-line quadrature hybrid 36b, respectively. The
circuit element sub-layer 80 also includes the input port 30, the
feed ports 32b and 32d, the circuit element 54, and the circuit
element 62.
[0038] The transmission line segment 92 extends from the input port
30 to the transmission line segment 93, which extends from the
transmission line segment 92 to an open end 108. The transmission
line segment 94 extends from a resistor 110 of the coupled-line
quadrature hybrid 36a to the circuit element 54, which extends from
the transmission line segment 94 to the feed port 32b. The
transmission line segment 96 extends from a resistor 112 of the
coupled-line quadrature hybrid 36b to the circuit element 62. The
circuit element 62 extends from the transmission line segment 96 to
the feed port 32d. As described above, the coupled-line quadrature
hybrids 36a and/or 36b may have characteristic impedances that are
different than the characteristic impedance of the input port 30
and/or the feed ports 32. The resistors 110 and 112 may each have
any value of resistance. For example, in the exemplary embodiment
of the feed network 12, the resistance value of the resistors 110
and 112 is selected as approximately 50 Ohms.
[0039] FIG. 4c illustrates the bonding layer 68. The bonding layer
68 may each include one or more openings, vias, and/or other
structures 114 that enable electrical and/or other connections to
be made to the printed circuit 64, between various elements of the
circuit elements layers 66 and 70, and/or between the ground plane
layers 98a and 98b. The bonding layer 68 may have any dielectric
constant. Examples of suitable materials for the bonding layer 68
include, but are not limited to, ceramic, rubber, fluoropolymer,
composite material, fiber-glass, plastic, and/or the like.
[0040] FIG. 4d illustrates the circuit element layer 66. The side
82 of the substrate 74 having the circuit element layer 66 is
visible in FIG. 4d. The circuit element sub-layer 78 extends on the
side 82 and includes the transmission line segment 86, the
transmission line segment 87, the transmission line segment 88, and
the transmission line segment 90. As described above, the segments
86 and 87 define portions of the Marchand balun 34, while the
segments 88 and 90 define portions of the coupled-line quadrature
hybrid 36a and the coupled-line quadrature hybrid 36b,
respectively. The circuit element sub-layer 78 includes the feed
ports 32a and 32c, the circuit element 46, the circuit element 44,
the circuit element 52, and the circuit element 60.
[0041] The transmission line segment 86 extends from an electrical
ground short 116 to the circuit element 46. The transmission line
segment 90 extends from the circuit element 46 to the circuit
element 60, which extends from the transmission line segment 90 to
the feed port 32c. The transmission line segment 87 extends from an
electrical ground short 118 to the circuit element 44. The
transmission line segment 88 extends from the circuit element 44 to
the circuit element 52, which extends from the transmission line
segment 88 to the feed port 32a. As can be seen in FIG. 4d, the
transmission line segments 86 and 87 are separated by a gap G in
the x-y plane, with the circuit elements 44 and 46 provided on
opposite sides of the gap G. The gap G is a segment of transmission
line (defined by the intersection of transmission line segments 92
and 93 shown in FIG. 4b) that extends between the transmission line
segments 86 and 87, and thus between the first and second
transmission line sections 154 and 156 (FIG. 5) of the Marchand
balun 34.
[0042] FIG. 5 is a plan view of the printed circuit 64 illustrating
an overlay of the circuit element layers 66 and 70. Various
components of the circuit element layers 66 and 70 are visible
through the ground plane layer 98a, the substrate 74 (FIGS. 3 and
4d), and the bonding layer 68 (FIGS. 3 and 4c) to illustrate an
overlay of the various components of the circuit element layers 66
and 70.
[0043] The transmission line segments 86 and 92 of the circuit
element layers 66 and 70, respectively, define a first transmission
line section 154 of the Marchand balun 34. In the exemplary
embodiment of the printed circuit 64, the transmission line
segments 86 and 92 are offset coupled (i.e., are offset from each
other in the x and/or y direction). Alternatively, the transmission
line segments 86 and 92 are broadside coupled (i.e., aligned with
each other in the x and y directions).
[0044] The transmission line segments 87 and 93 of the circuit
element layers 66 and 70, respectively, define the second
transmission line section 156 of the Marchand balun 34. In the
exemplary embodiment of the printed circuit 64, the transmission
line segments 87 and 93 are offset coupled. Alternatively, the
transmission line segments 87 and 93 are broadside coupled.
[0045] The transmission line segments 88 and 94 of the circuit
element layers 66 and 70, respectively, define the single
transmission line section 150 of the coupled-line quadrature hybrid
36a. In the exemplary embodiment of the printed circuit 64, the
transmission line segments 88 and 94 are broadside coupled. But,
the transmission line segments 88 and 94 may alternatively be
offset coupled.
[0046] The coupler segments 90 and 96 of the circuit element layers
66 and 70, respectively, define the single transmission line
section 152 of the coupled-line quadrature hybrid 36b. In the
exemplary embodiment of the printed circuit 64, the transmission
line segments 90 and 96 are broadside coupled. But, the
transmission line segments 90 and 96 may be offset coupled in some
alternative embodiments.
[0047] The feed network 12 is not limited to including a single
Marchand balun 34 and two coupled-line quadrature hybrids 36. For
example, FIG. 6 is a schematic block diagram of another exemplary
embodiment of a feed network 212. The feed network 212 includes at
least three RF devices constructed in a suspended-substrate
stripline configuration. In the exemplary embodiment of the feed
network 12, the three RF devices include a single coupled-line
quadrature hybrid 236 and two Marchand baluns 234a and 234b.
Specifically, the feed network 212 includes an input port 230, four
feed ports 232, the coupled-line quadrature hybrid 236, and the two
Marchand baluns 234. The four exemplary feed ports 232 are labeled
as feed ports 232a, 232b, 232c, and 232d. The input port 230 may be
referred to herein as a "sum port". The Marchand baluns 234a and
234b may each be referred to herein as a "first" and/or a "second"
balun. The coupled-line quadrature hybrid 236 may be referred to
herein as a "first" quadrature hybrid. Each of the feed ports
232a-d may be referred to respectively herein as a "first", a
"second", a "third", and/or a "fourth" feed port.
[0048] The coupled-line quadrature hybrid 236 and the Marchand
baluns 234a and 234 are operatively connected between the input
port 230 and the feed ports 232 for feeding RF energy between the
input port 230 and the feed ports 232. The coupled-line quadrature
hybrid 236 is configured to divide an RF signal into two RF signals
that have approximately equal power amplitudes and a phase
difference of 90.degree.. Each of the Marchand baluns 234 is
configured to divide an RF signal into two RF signals with
approximately equal power amplitudes and a phase difference of
180.degree..
[0049] The Marchand baluns 234 and the coupled-line quadrature
hybrid 236 are electrically arranged relative to the input port 230
and the feed ports 232 such that the four feed ports 232 are
configured with approximately equal power amplitude and a
progressive 90.degree. phase shift. For example, in the exemplary
embodiment of the feed network 212, the coupled-line quadrature
hybrid 236 is electrically connected between the input port 230 and
the Marchand baluns 234, while the Marchand baluns 234 are
electrically connected between the coupled-line quadrature hybrid
234 and the feed ports 232. Specifically, and as shown in FIG. 6,
the coupled-line quadrature hybrid 236 is electrically connected
between the input port 230 and each of the Marchand baluns 234a and
234b. The Marchand balun 234a is electrically connected between the
coupled-line quadrature hybrid 236 and the feed ports 232a and
232b. The Marchand balun 234b is electrically connected between the
coupled-line quadrature hybrid 236 and the feed ports 232c and
232d.
[0050] During operation of the feed network 212, the coupled-line
quadrature hybrid 236 receives an input RF signal 238 from the
input port 230. The coupled-line quadrature hybrid 236 divides the
input RF signal 238 into two intermediate RF signals 240 and 242
that have approximately equal amplitudes and a phase difference of
90.degree.. The intermediate RF signals 240 and 242 have respective
phases of 0.degree. and 90.degree., relative to the phase of the
input RF signal 238. The intermediate RF signal 240 may be referred
to herein as a "first" intermediate RF signal, while the
intermediate RF signal 242 may be referred to herein as a "second"
intermediate RF signal.
[0051] The Marchand balun 234a receives the intermediate RF signal
240 from the coupled-line quadrature hybrid 236 and divides the
intermediate RF signal 240 into two feed RF signals 248 and 250
that have approximately equal power amplitudes and a phase
difference of 180.degree.. Specifically, the feed RF signals 248
and 250 have phases of 0.degree. and 180.degree., respectively. The
feed port 236a receives the feed RF signal 248 from the Marchand
balun 234a such that the feed port 236a is configured with the
0.degree. phase of the feed RF signal 248. The feed RF signal 248
may be referred to herein as "first" feed RF signal.
[0052] The feed port 236b receives the feed RF signal 250 from the
Marchand balun 234a such that the feed port 236b is configured with
the 180.degree. phase of the feed RF signal 250. The feed RF signal
250 may be referred to herein as "second" feed RF signal.
[0053] The Marchand balun 234b receives the intermediate RF signal
242 from the coupled-line quadrature hybrid 236. The Marchand balun
234b divides the intermediate RF signal 242 into two feed RF
signals 256 and 258 that have approximately equal power amplitudes
and a phase difference of 180.degree.. Specifically, the feed RF
signals 256 and 258 have respective phases of 90.degree. and
270.degree.. The feed port 236c receives the feed RF signal 256
from the Marchand balun 234b. The feed port 236c is thus configured
with the 90.degree. phase of the feed RF signal 256. The feed port
236d receives the feed RF signal 258 from the Marchand balun 234b.
The feed port 236d is thus configured with the 270.degree. phase of
the feed RF signal 258. The feed RF signals 256 and 258 may be
referred to herein as "third" and "fourth" feed RF signals,
respectively.
[0054] As should be appreciated from the above description and FIG.
6, the coupled-line quadrature hybrid 236 and the Marchand baluns
234a and 234b are electrically arranged relative to the input port
230 and the feed ports 236 such that feed network 12 is configured
with approximately equal power amplitude and a progressive
90.degree. phase shift of 0.degree., 90.degree., 180.degree., and
270.degree.. The angular direction of the progressive phase shift
may either a right hand direction (i.e., counter-clockwise) and/or
a left hand direction (i.e., clockwise).
[0055] The coupled-line quadrature hybrid 236 may have any
characteristic impedance, such as, but not limited to,
approximately 70.7 Ohms, approximately 50 Ohms, and/or the like. In
some embodiments, the coupled-line quadrature hybrid 236 has
characteristic impedance that is different than a characteristic
impedance of the input port 230 and/or the feed ports 232. For
example, in the exemplary embodiment of the feed network 12, the
coupled-line quadrature hybrid 236 has a characteristic impedance
of approximately 70.7 Ohms, while the input port 230 and the feed
ports 232 each have a characteristic impedance of approximately 50
Ohms.
[0056] In the exemplary embodiment of the feed network 212, the
coupled-line quadrature hybrid 236 includes only a single
transmission line section. The single transmission line section of
the coupled-line quadrature hybrid 236 may be a uniformly-coupled
transmission line section or may be a non-uniformly coupled
transmission line section. The two transmission line segments of
the transmission line section of the coupled-line quadrature hybrid
236 may be offset coupled or may be broadside coupled. The
transmission line section of the coupled-line quadrature hybrid 236
may have any electrical length. In the exemplary embodiment of the
feed network 12, the transmission line section of the coupled-line
quadrature hybrid 236 has an electrical length of one-quarter of a
wavelength at the center frequency of operation. Examples of other
electrical lengths of the transmission line section of the
coupled-line quadrature hybrid 236 include, but are not limited to,
three-quarters of a wavelength, five-quarters of a wavelength,
and/or the like. In some alternative embodiments, the coupled-line
quadrature hybrid 236 includes more than one transmission line
section. For example, multiple transmission line sections having
electrical lengths of one-quarter of a wavelength may be connected
in series to widen the bandwidth of the coupled-line quadrature
hybrid 236. The transmission line section of the coupled line
quadrature hybrid 236 may be referred to herein as a "quadrature
coupler".
[0057] In the exemplary embodiment of the feed network 212, each
Marchand balun 234a and 234b includes two transmission line
sections. Each transmission line section of each Marchand balun 234
may be a uniformly-coupled transmission line section or may be a
non-uniformly coupled transmission line section. The two
transmission line segments of each transmission line section of
each Marchand balun 234 may be offset coupled or may be broadside
coupled. Each transmission line section of each Marchand balun 234
may have any electrical length. In the exemplary embodiment of the
feed network 212, each transmission line section of each Marchand
balun 234 has an electrical length of one-quarter of a wavelength
at the center frequency of operation. Examples of other electrical
lengths of each transmission line section of each Marchand balun
234 include, but are not limited to, three-quarters of a
wavelength, five-quarters of a wavelength, and/or the like. One or
both of the marchand baluns 34 may include more than two
transmission line sections in some alternative embodiments. In some
embodiments, one or both of the Marchand baluns 234 includes
multiple transmission line sections having electrical lengths of
one-quarter of a wavelength that are connected in series to widen
the bandwidth of the Marchand balun 234.
[0058] The embodiments described and/or illustrated herein may
provide a five-port microwave device with one sum port and four
feed ports, wherein the feed ports have equal amplitude power and a
progressive 90.degree. phase shift.
[0059] The embodiments described and/or illustrated herein may
provide a feed network that operates over a wider frequency band
than at least some known feed networks. The embodiments described
and/or illustrated herein may provide a feed network having a
bandwidth that enables an associated antenna to communicate with
one or more devices.
[0060] The embodiments described and/or illustrated herein may
provide a feed network that is smaller than at least some known
feed networks. The embodiments described and/or illustrated herein
may provide an array that is capable of including more feed
networks, and thus more antennas, than at least some known arrays
of antennas.
[0061] The embodiments described and/or illustrated herein may
provide a feed network that is less expensive to fabricate than at
least some known feed networks.
[0062] In one embodiment, a feed network is comprised of a total of
three devices, including one or two coupled-line quadrature hybrids
and one or two Marchand baluns. Each coupled-line quadrature hybrid
consists of a single quadrature coupler providing two outputs with
approximately equal amplitude power and a phase difference of
90.degree., as opposed to two or more couplers in tandem. Each
Marchand balun consists of two offset-coupled transmission line
sections separated by a gap, from opposite sides of which gap two
output ports are connected, the two output ports having
approximately equal amplitude power and a phase difference of
180.degree.. The three devices are built in a suspended-substrate
stripline configuration, providing a five-port microwave device
with one sum port and four feed ports. The feed ports have equal
amplitude power and a progressive 90.degree. phase shift.
[0063] Optionally, each quadrature coupler consists of at least one
uniformly-coupled transmission line section, each with an
electrical length of one-quarter of a wavelength at the center
frequency of operation, providing outputs with approximately equal
amplitude power and a phase difference of 90.degree.. Optionally,
each quadrature coupler consists of a non-uniformly coupled
transmission line section, providing two outputs with approximately
equal amplitude power and a phase difference of 90.degree..
[0064] Optionally, each Marchand balun consists of at least two
uniformly-coupled transmission line sections, each with an
electrical length of one-quarter of a wavelength at the center
frequency of operation, providing outputs with approximately equal
amplitude power and a phase difference of 180.degree.. Optionally,
each Marchand balun consists of a non-uniformly coupled
transmission line section, providing outputs with approximately
equal amplitude power and a phase difference of 180.degree..
[0065] In some embodiments, the at least one Marchand balun
comprises a first balun, the at least one coupled-line quadrature
hybrid comprises first and second quadrature hybrids, and the four
feed ports comprise first, second, third, and fourth feed ports.
The first balun is electrically connected between the input port
and the first and second quadrature hybrids and is configured to
divide an input RF signal into first and second intermediate RF
signals with approximately equal power amplitudes and a phase
difference of 180.degree.. The first quadrature hybrid is
electrically connected between the first balun and the first and
second feed ports and is configured to divide the first
intermediate RF signal into first and second feed RF signals having
phases of 0.degree. and 90.degree., respectively. The second
quadrature hybrid is electrically connected between the first balun
and the third and fourth feed ports and is configured to divide the
second intermediate RF signal into third and fourth feed RF signals
having phases of 180.degree. and 270.degree., respectively.
[0066] In some embodiments, the at least one Marchand balun
comprises first and second baluns, the at least coupled-line
quadrature hybrid comprises a first quadrature hybrid, and the four
feed ports comprise first, second, third, and fourth feed ports.
The first quadrature hybrid is electrically connected between the
input port and the first and second baluns and is configured to
divide an input RF signal into first and second intermediate RF
signals with approximately equal power amplitudes and a phase
difference of 90.degree.. The first balun is electrically connected
between the first quadrature hybrid and the first and third feed
ports and is configured to divide the first intermediate RF signal
into first and third feed RF signals having phases of 0.degree. and
180.degree., respectively. The second balun is electrically
connected between the first quadrature hybrid and the second and
fourth feed ports and is configured to divide the second
intermediate RF signal into second and fourth feed RF signals
having phases of 90.degree. and 270.degree., respectively.
[0067] In some embodiments, a four-layer printed circuit board
stackup is used, with the upper substrate core providing two
conductive layers for circuitry, the lower substrate core providing
another two conductive layers for circuitry, and the at least one
bonding film between the cores providing physical separation
between the lower side of the upper substrate core and the upper
side of the lower substrate core.
[0068] Optionally, the feed network is configured to operate over a
bandwidth of at least approximately 10 percent. The feed network
optionally has a width of less than approximately 2.0 inches (50.8
mm).
[0069] As used herein, an element or step recited in the singular
and proceeded with the word "a" or "an" should be understood as not
excluding plural of said elements or steps, unless such exclusion
is explicitly stated. Furthermore, references to "one embodiment"
or "an embodiment" are not intended to be interpreted as excluding
the existence of additional embodiments that also incorporate the
recited features. Moreover, unless explicitly stated to the
contrary, embodiments "comprising" or "having" an element or a
plurality of elements having a particular property may include
additional elements not having that property.
[0070] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. In addition, many modifications may be
made to adapt a particular situation or material to the teachings
of the invention without departing from its scope. Dimensions,
types of materials, orientations of the various components, and the
number and positions of the various components described herein are
intended to define parameters of certain embodiments, and are by no
means limiting and are merely exemplary embodiments. Many other
embodiments and modifications within the spirit and scope of the
claims will be apparent to those of skill in the art upon reviewing
the above description. The scope of the invention should,
therefore, be determined with reference to the appended claims,
along with the full scope of equivalents to which such claims are
entitled. In the appended claims, the terms "including" and "in
which" are used as the plain-English equivalents of the respective
terms "comprising" and "wherein." Moreover, in the following
claims, the terms "first," "second," and "third," etc. are used
merely as labels, and are not intended to impose numerical
requirements on their objects. Further, the limitations of the
following claims are not written in means--plus-function format and
are not intended to be interpreted based on 35 U.S.C. .sctn.112,
sixth paragraph, unless and until such claim limitations expressly
use the phrase "means for" followed by a statement of function void
of further structure.
* * * * *